Among the scents of flowers and spring rains, there is something else: the pungent odor of decaying fish.

You may have noticed the smell if you've been downtown or near Lake Erie this week.

The smell is from thousands of dead fish -- shad -- washing up on shore.

The annual shad die-off is underway all along the lakeshore. But take heart, Clevelanders. The smell gets far, far more intense as you head East, all the way to Buffalo.

Biologists say this is a natural event caused by temperature changes that the shad cannot withstand.

"They're very sensitive to temperatures and they don't do good when temperatures change a lot,"said CareyKnight."They're very oily and break down and be kind of smelly. You probably want to keep your dogs away from them."

Knight says the shad pose no threat and are a food source for many different animals including other fish, herons, ducks and gulls.